WASHINGTON - About 11,000 upstate New York homeowners would avert increases in their flood insurance premiums under bipartisan legislation introduced in Congress last month, according to Democratic Sen. Chuck Schumer.

Under the Homeowner Flood Insurance Affordability Act, premium increases in National Flood Insurance Program policies would be delayed for about four years from the bill's date of passage, until the Federal Emergency Management Agency completes an affordability study.

According to Schumer's office, the legislation would apply retroactively to homeowners who recently purchased a home in a flood zone. The office said rate hikes for those homeowners took effect Oct. 1.

"Instituting rate hikes before the affordability study can be completed is putting the cart before the horse," Schumer told reporters Thursday. "Plus, those homeowners that are ultimately affected should have adequate time to plan for the rate increases."

Many homeowners in New York and New Jersey are facing higher flood insurance rates as a result of Superstorm Sandy and tropical storms Lee and Irene that struck coastal and upstate areas over the last several years.

Although some homeowners with flood insurance have grandfathered rates that currently protect them from rate increases, they will face higher rates when local flood maps are updated.

The number of homeowners facing higher rates varies by region, ranging from 4,128 in the Hudson Valley to 1,976 in the Southern Tier, 1,719 in western New York, and 1,255 in the Rochester-Finger Lakes area.

A recent Rand Corporation study commissioned by New York City estimates property owners in the highest-risk areas could face annual premium increases of $5,000 to $10,000 that could lower their property values.

Schumer said some homeowners may drop their flood insurance if rates climb too high, threatening the National Flood Insurance Program's viability. Many have mortgages that require them to have flood insurance, but there's no similar requirement for those who don't have a mortgage.

The Obama administration has requested a more narrowly focused remedy that would grant waivers from higher premiums to low-income homeowners.

The reason for the higher rates is a 2012 law known as Biggert-Waters, which calls for increasing premiums 25 percent each year for four years to make up for deficits caused by massive storms such as Hurricane Katrina and to bring National Flood Insurance Program operations more in line with their real costs.

In the last year alone, FEMA has paid out more than $7.8 billion in Sandy-related flood insurance claims.

The National Flood Insurance Program traditionally has charged premiums covering only 40 to 45 percent of the program's full cost, with taxpayers subsidizing the rest.

In January, Congress authorized an increase in federal borrowing to keep the program operating following Superstorm Sandy. The increase aimed to allow FEMA to reimburse homeowners and businesses for flood insurance claims for Sandy-related damage.

Schumer and Democratic Sen. Kirsten Gillibrand of New York are among 20 Senate cosponsors of the Homeowner Flood Insurance Affordability Act, introduced by Democratic Sen. Robert Menendez of New Jersey and Republican Sen. Johnny Isakson of Georgia.

Schumer said he's hoping to get the legislation through the Senate by attaching it as an amendment to a fiscal 2014 defense authorization bill, a possible fiscal 2014 budget bill, or a spending bill.

The House version of the bill, introduced by Republican Rep. Michael Grimm of Staten Island, has 119 cosponsors, including New York Reps. Chris Collins, R-Clarence, and Sean Maloney, D-Cold Spring.

The budget watchdog group Taxpayers for Common Sense says the legislation would "gut the heart'' of reforms designed to make the National Flood Insurance Program more self-sufficient.

Taxpayers for Common Sense has suggested that a more fiscally responsible solution could include mitigation assistance, a slower phase-in of premium rate increases, temporary premium assistance for low-income homeowners and fixes to errors in flood maps.